DE112005001951B4 - Piezoelectric ceramic composition and its use - Google Patents

Abstract

The piezoelectric ceramic composition comprising a main component represented by the general formula {(1 - n) (Ag _1-x Li _{x) m} (Nb _1-y Ta _y) O ₃ - n (M1, M2) M3O _3} is (wherein M1 represents a trivalent metal element, M2 represents a monovalent metal element and M3 represents a tetravalent metal element), where x, y, m and n are defined as:
0.075 ≤ x <0.40;
0 ≤ y <0.2;
0.98 ≤ m ≤ 1.0 and
0.01 ≤ n ≤ 0.1.

Description

Technical area

The The present invention relates to piezoelectric ceramic compositions and piezoelectric elements. In detail, the present invention relates Invention lead-free piezoelectric ceramic compositions, the be used in a variety of piezoelectric elements can, and relates to piezoelectric elements such as piezoelectric oscillators, piezoelectric actuators, piezoelectric filters, piezoelectric Buzzer and piezoelectric sensors using piezoelectric Ceramic compositions are produced.

State of the art

As raw materials for piezoelectric elements such as piezoelectric oscillators common piezoelectric ceramic compositions of Pb (Ti, Zr) O ₃ (lead zirconate titanate), or _PbTiO3 (lead titanate) as the main component, is used.

There but these types of piezoelectric ceramic compositions contain a Pb ingredient, they are environmental not preferred. Therefore, recently, lead-free piezoelectric materials, the no Pb component included, required.

Therefore, a piezoelectric ceramic composition having a main component having a composition represented by the general formula (Ag _1-x Li _x ) (Nb _1-y Ta _y ) O _{3 has been} previously described, wherein 0.075 ≦ x <0.40 and 0 ≦ y <0.20, and an additional ingredient (not more than 5 parts by weight) containing at least one of an Mn oxide and a Si oxide disclosed (Patent Document 1).

A piezoelectric element must generally have a high electromechanical coupling factor k _33, which indicates a conversion efficiency in the conversion of applied between electrodes of a piezoelectric electric energy into mechanical energy. In Patent Document 1, a piezoelectric element having an electromechanical coupling factor k ₃₃ of 20% or more, which is a value withstand practical use, can be obtained by using a piezoelectric ceramic composition having the above-mentioned composition.

• Patentschrift 1: ungeprüfte japanische Patentanmeldung, Veröffentlichung Nr. JP 2002-68836 A
• Patentschrift 2: PCT japanische Übersetzung Patent, Veröffentlichung Nr. JP 2004-507432 A

Further, Patent Document 2 discloses a ceramic material mainly used for a capacitor. The ceramic material contains two different types of constituents which are present in mutually different phases and each have a perovskite structure containing Ag in the A site and Nb and Ta in the B site. Specifically, the use of a composition (Ag _1-y M ^III _y ) ((Nb _1-x Ta _x ) _1-y M ^IV _y ) O ₃ (wherein M ^{III represents} Bi or a rare earth metal, M ^IV In, Sc or Ga represents and 0.35 ≦ x <0.5 and 0 ≦ y ≦ 0.1) or a composition (Ag _1-y M ^III _y ) ((Nb _1-x Ta _x ) _1-y M ^IV _y ) O ₃ (wherein M ^{III represents} Ba, Ca, Pb or Sr, M ^{IV represents} Sn or Zr and 0.35 ≤ x ≤ 0.5 and 0 ≤ y ≤ 0.1). Further, it is disclosed that a microwave device having a high dielectric constant, ie, ε> 300, a low dielectric loss, and a small TK _{ε can be} obtained by using a composition disclosed in Patent Document 1.

• Patent Document 1: Unexamined Japanese Patent Application, Publication No. JP 2002-68836 A
• Patent Document 2: PCT Japanese Translation Patent, Publication No. JP 2004-507432 A

From the DE 101 41 293 A1 Further, a piezoelectric ceramic composition and a corresponding piezoelectric ceramic device is known, wherein the composition has the general formula (Ag _1-x Li _x ) _m (Nb _1-y Ta _y ) O ₃ , with 0.075 ≤ x <0.40 and 0 ≤ y <0.2. The ceramic contains up to 5 wt .-% Mn and Si oxide.

Disclosure of the invention

Problems to be solved by the invention

In general, as described above, piezoelectric elements must have a high electromechanical coupling factor k ₃₃ or a high piezoelectric constant d ₃₃ . When using a piezoelectric element as a piezoelectric filter or piezoelectric oscillator, which are built on an electronic circuit, the piezoelectric element must have a suitably high relative dielectric constant εr (= ε / ε ₀ , ε: dielectric constant, ε ₀ : dielectric constant at vacuum).

Around a piezoelectric element such as a piezoelectric filter or a piezoelectric oscillator on an electronic To use circuit must have the impedance of the piezoelectric Elements are adjusted to a predetermined value. In the Determining the impedance is the capacitance of this piezoelectric element a critical factor.

The capacity a piezoelectric element is, as is well known, directly proportional to the relative dielectric constant εr. If the relative dielectric constant εr of a piezoelectric Material is high, therefore, a target impedance can be easily realized even if the area of a piezoelectric element due to miniaturization miniaturized becomes.

There as described above, a target impedance can be easily provided, if the relative dielectric constant εr of a piezoelectric Material is high, a suitable high relative dielectric constant εr for miniaturization a piezoelectric element required.

The relative dielectric constant εr of in Patent Document 1 disclosed piezoelectric ceramic composition but has a low value of 350 or less. Therefore, it is disadvantageously difficult to obtain a target impedance.

Further, in Patent Document 1, some piezoelectric ceramic compositions have a piezoelectric constant d ₃₃ which is less than 50. Further, which is problematic, a high electromechanical coupling factor k ₃₃ can not be stably realized.

In Patent Document 2, a ceramic material having a high relative dielectric constant εr is disclosed. However, the relative dielectric constant εr is less than 600 at a maximum. Thus, no sufficient relative dielectric constant εr is achieved. Further, since the ceramic material disclosed in Patent Document 2 is used for a microwave device, disadvantageously, no suitable piezoelectric properties such as an electromechanical coupling factor k ₃₃ and a piezoelectric constant d _{33 are} provided.

The present invention has been accomplished in view of the above-mentioned problems. An object of the present invention is to provide highly reliable lead-free piezoelectric ceramic compositions having a suitably high relative dielectric constant and good piezoelectric properties such as an electromechanical coupling factor k ₃₃ and a piezoelectric constant d ₃₃ . Another object of the present invention is to provide piezoelectric elements which are manufactured by means of such piezoelectric ceramic compositions.

Means for releasing the problem

The present inventor has intensively studied on lead-free perovskite complex oxide (general formula: ABO ₃ ) to realize the above-mentioned objects, and has found that a piezoelectric ceramic composition having a suitably high relative permittivity εr and a good piezoelectric property stably having a high electromechanical coupling factor k ₃₃ and a high piezoelectric constant d ₃₃ can be obtained even if the composition does not contain lead by using a composition in which a second complex oxide having an A-site, the solid-dissolved Bi and K, Na, Li or Ag, and a B site containing Ti, Zr, Sn or Hf dissolved in the solid, is dissolved in a first complex oxide represented by (Ag, Li) (Nb, Ta) O ₃ , and the molar ratios of each constituent are suitably controlled.

Further is solid-solubilized Bi in the A site of the second complex oxide a trivalent metal element, and K, Na, Li and Ag, which are in the A site dissolved solids are all monovalent metal elements, and those in the B-site solids dissolved Ti, Zr, Sn and Hf are all tetravalent metal elements. Therefore It is suggested that one by using metal element generated with the same valences as each of these metal elements Composition similar Functions and effects may have.

The present invention has been accomplished based on these findings. Is shown, the piezoelectric ceramic composition contains a main component represented by the general formula {n (M1, M2) M3O ₃ (1 - - n) (Ag _1-x Li _{x) m} (Nb _1-y Ta _y) O _3} (where M1 represents a trivalent metal element, M2 represents a monovalent metal element and M3 represents a tetravalent metal element), and x, y, m and n are expressed as 0.075 ≤ x <0.40, 0 ≤ y <0.2, 0.98 ≤ m ≤ 1.0 and 0.01 ≤ n ≤ 0.1.

in the The single is in the piezoelectric ceramic composition of the present invention M1 Bi, M2 is at least one element selected from the group consisting from K, Na, Li and Ag and M3 is selected from at least one element the group consisting of Ti, Zr, Sn and Hf.

The present inventor has continued to study intensively, and accordingly, similarly to the above, has revealed the fact that a piezoelectric ceramic composition having a suitably high relative permittivity εr and a good piezoelectric property stably has a high electromechanical coupling factor k ₃₃ and a high piezoelectric constant d ₃₃ can also be obtained by using a perovskite oxide as a second complex oxide in which a divalent metal element (for example, at least one element selected from Ba, Sr, Ca and Mg) is solid-solubilized in the A site and a tetravalent metal element (e.g. at least one element selected from Ti, Zr, Sn and Hf) is dissolved in the B-site.

In other words, the piezoelectric ceramic composition of the present invention may contain a main component represented by the general formula {(1-n) (Ag _1-x Li _x ) _m (Nb _1-y Ta _y ) O ₃ -nM4M5O ₃ }) M4 represents a divalent metal element and M5 represents a tetravalent metal element), and x, y, m and n are expressed as 0.075 ≦ x <0.40, 0 ≦ y <0.2, 0.98 ≦ m ≦ 1.0, and 0 , 01 ≤ n ≤ 0.1.

in the The single is in the piezoelectric ceramic composition of the present invention M4 selected at least one element from the group consisting of Ba, Sr, Ca and Mg and M5 is at least an element selected from the group consisting of Ti, Zr, Sn and Hf.

Farther According to the invention Use of a piezoelectric ceramic according to claims 5 and 6 taught.

there comprises a piezoelectric according to the invention Element outer electrodes, the on the surface one of the piezoelectric ceramic composition described above formed ceramic sintered body are arranged.

Further comprises the piezoelectric according to the invention Element an embedded in the ceramic sintered inner electrode.

Advantageous effect of the invention

According to the piezoelectric material ceramic composition described above, a main component is represented by the general formula {(1-n) (Ag _1-x Li _x ) _m (Nb _1-y Ta _y ) O ₃ -n (M1, M2) M ₃ O ₃ } (where M1 represents a trivalent metal element, M2 represents a monovalent metal element and M3 represents a tetravalent metal element), and x, y, m and n are represented as 0.075 ≦ x <0.40, 0 ≦ y <0.2, 0, 98 ≤ m ≤ 1.0 and 0.01 ≤ n ≤ 0.1. Therefore, the piezoelectric ceramic composition has a suitably high relative dielectric constant εr and a good piezoelectric property, stably having a high electromechanical coupling factor k ₃₃ and a high piezoelectric constant d ₃₃ .

Further, M1 is Bi, M2 is at least one element selected from the group consisting of K, Na, Li and Ag, and M3 is at least one element selected from the group consisting of Ti, Zr, Sn and Hf. Therefore, the piezoelectric ceramic composition of the present invention a high relative dielectric constant of 600 or more, an electromechanical coupling factor k ₃₃ of 25% or more and a piezoelectric constant d ₃₃ of 50 pC / N or more. The piezoelectric ceramic composition also has a good piezoelectric property reaching a Curie temperature of 200 ° C or more.

Further, when the main constituent of a piezoelectric ceramic composition is represented by the general formula {(1-n) (Ag _1-x Li _x ) _m (Nb _1-y Ta _y ) O ₃ -nM4M5O ₃ } (wherein M 4 represents a divalent metal element and M5 represents a tetravalent metal element) and x, y, m and n are 0.075 ≦ x <0.40, 0 ≦ y <0.2, 0.98 ≦ m ≦ 1.0 and 0.01 ≦ n ≦ 0.1 are set, the piezoelectric ceramic composition also has a suitably high relative dielectric constant εr and a good piezoelectric property, and similarly as above, has a high electromechanical coupling factor k ₃₃ and a high piezoelectric constant d ₃₃ .

Further, in the piezoelectric ceramic composition of the present invention, when M4 is at least one element selected from the group consisting of Ba, Sr, Ca and Mg and M5 is at least one element selected from the group consisting of Ti, Zr, Sn and Hf, the piezoelectric element of the present invention has Similar to the above, a high relative dielectric constant of 600 or more, an electromechanical coupling factor k ₃₃ of 25% or more, a piezoelectric constant d ₃₃ of 50 pC / N or more, and a good piezoelectric property exhibiting a Curie temperature of 200 ° or more achieved.

at the above mentioned piezoelectric element can Furthermore, due to the arrangement of external electrodes on the surface of a of the piezoelectric ceramic composition described above formed ceramic sintered body different types of piezoelectric elements with a good one piezoelectric property and excellent reliability be provided.

There further in the above-mentioned ceramic sintered body an inner electrode is embedded, similar to the above Types of piezoelectric elements with a good piezoelectric property and excellent reliability be provided.

Brief description of the drawings

1 is a perspective view of a piezoelectric oscillator as a piezoelectric element according to an embodiment of the invention.

2 is a cross-sectional view along the line AA of 1 ,

reference numeral

1

piezoelectric Ceramic (ceramic sintered body)

2

inner electrode

3

outer electrode

4

outer electrode

Best mode of carrying out the invention

When next time be inventive embodiments described in more detail.

A piezoelectric ceramic composition according to a first embodiment of the present invention is represented by the general formula (A): (1-n) (Ag _1-x Li _x ) _m (Nb _1-y Ta _y ) O ₃ -n (M1, M2) M ₃ O ₃ (A).

• (1) 0,075 ≤ x < 0,40;
• (2) 0 ≤ y < 0,2;
• (3) 0,98 ≤ m ≤ 1,0 und
• (4) 0,01 ≤ n ≤ 0,1.

The molar ratios x, y, m and n satisfy the following expressions (1) to (4):

• (1) 0.075 ≦ x <0.40;
• (2) 0 ≦ y <0.2;
• (3) 0.98 ≤ m ≤ 1.0 and
• (4) 0.01 ≦ n ≦ 0.1.

In other words, this piezoelectric ceramic composition is a composite containing two kinds of complex oxides each having a perovskite structure. A second complex oxide (M1, M2) M3O ₃ is in a first complex oxide (Ag, Li) (Nb, Ta) O ₃ solid-solved. M1 is a trivalent metal element, M2 is a monovalent metal element, and M3 is a tetravalent metal element, and thus the charges are balanced based on the chemical structure. However, the ratio between M1 and M2 may differ slightly from 1: 1 as long as the property is not affected.

Further, the piezoelectric ceramic composition of the present invention is produced so that the general formula (A) satisfies the expressions (1) to (4). Therefore, a piezoelectric ceramic composition having a suitably high relative dielectric constant εr and a good piezoelectric property can be obtained which stably has a high electromechanical coupling factor k ₃₃ and a high piezoelectric constant d ₃₃ .

Specifically, examples of the trivalent metal element M1 include Bi, La, Nd, Sm, Gd, Y and Sc. Bi is particularly preferred. Examples of the monovalent metal element M2 include Li, Na, K and Ag. at By using these metal elements M1 to M3, the piezoelectric ceramic composition having a high relative permittivity εr of 600 or more, an electromechanical coupling factor k ₃₃ of 25% or more, a piezoelectric ceramic can be used Constant d ₃₃ of 50 pC / N or more and a good piezoelectric property reaching a Curie temperature of 200 ° C or more can be provided.

Next, the reasons that the molar ratios of x, y and m each element of the main component and the molar ratio n of the second complex oxide (M1, M2) M3O ₃ to the first complex oxide (Ag, Li) (Nb, Ta) O _{3 are} limited to the ranges specified by expressions (1) to (4).

(1) molar ratio x

One under a high temperature atmosphere used piezoelectric Element must have a high Curie temperature Tc, which is a temperature is, in which a ferroelectric phase to a paraelectric or antiferroelectric phase is converted. When the molar ratio x Li is lower than 0.075, the Curie temperature Tc becomes 200 ° C or Lowered so that the temperature stability of a piezoelectric element is worsened.

If however, the molar ratio x is 0.4 or more, the sintering property is deteriorated, so that the insulation resistance is lowered. This makes the polarization treatment difficult.

Therefore is in this version the molar ratio x limited by Li to 0.075 ≦ x <0.40.

(2) molar ratio y

There Ta has the same function as Nb, Ta may need in the piezoelectric To be included ceramic composition. But if the molar ratio y from Ta to Nb is 0.2 or more, The Curie temperature Tc is lowered to 200 ° C or less, so that the temperature stability a piezoelectric element as in the molar ratio x is worsened.

Therefore is in this version the molar ratio y is limited from Ta to Nb to 0≤y <0.2.

(3) molar ratio m

If the molar ratio m of the component of the A site (Ag, Li) of the first complex oxide to the B-site (Nb, Ta) is less than 0.98 the amount of the B-site component (Nb, Ta) is too high. If against the molar ratio m higher is 1.0, the amount of the A-site component is too high. In both cases the sintering property is deteriorated, so that the insulation resistance is lowered. This makes polarization treatment difficult.

Therefore is in this version the molar ratio m is limited to 0.98 ≤ m ≤ 1.0.

(4) molar ratio n

Can .epsilon..sub.R the relative dielectric constant by adding a suitable amount of a second complex oxide (M1, M2) M3O ₃ to the first complex oxide (Ag, Li) (Nb, Ta) O be improved. ₃ When the molar ratio n of the second complex oxide (M1, M2) M3O ₃ for the first complex oxide (Ag, Li) (Nb, Ta) O ₃ is higher than 1.0, no high electromechanical coupling factor can be maintained k _33rd This makes the use of the piezoelectric ceramic composition unsuitable as a material of a piezoelectric filter or a piezoelectric oscillator. On the other hand, if the molar ratio n is less than 0.01, the relative dielectric constant εr becomes lower than 600. Thus, no desired relative dielectric constant εr can be provided. Therefore, the impedance matching is deteriorated when the piezoelectric element is miniaturized.

Therefore, in this embodiment, the molar ratio n of the second complex oxide (M1, M2) M3O O ₃ 0.01 ≤ ₃ for the first complex oxide (Ag, Li) (Ta, Nb, n) ≤ 0.1 is limited.

When next becomes a manufactured by means of the piezoelectric ceramic composition described above described piezoelectric element.

1 FIG. 15 is a perspective view of a piezoelectric oscillator as a piezoelectric element according to the first embodiment. FIG. 2 is a cross-sectional view along the line AA of 1 ,

In the piezoelectric element, two piezoelectric ceramics (piezoelectric ceramic sintered bodies 1a and 1b ) polarized in the direction of arrows B are monolithically stacked so that therebetween an inner electrode 2 is arranged, and external electrodes three and 4 are on the outer surfaces of the piezoelectric ceramic material body 1a and 1b educated.

The inner electrode 2 has a disc-shaped oscillating section 2a in the middle of the piezoelectric ceramic material body and a T-shaped extending portion 2 B that with the swinging section 2a at a point whose circumference is connected to. The T-shaped extending section 2 B is exposed on a side surface of the piezoelectric oscillator.

The outer electrodes three and 4 are on the outer surfaces of the first piezoelectric ceramic material body 1a or the second piezoelectric ceramic material body 1b formed so that they pass each other through the first and second piezoelectric ceramic material bodies 1a and 1b are facing. The outer electrodes three and 4 have disc-shaped oscillating sections 3a respectively. 4a at about the centers of the piezoelectric ceramic material bodies and T-shaped extending portions 3b and 4b that with the respective oscillating sections 3a and 4a at a point of each circumference of the same are connected to. The extending sections 3b and 4b are exposed on the opposite side surface of the piezoelectric oscillator.

The extending part 2 B is with an outer terminal 6a by means of a supply line 5a connected, and the outer sections 3b and 4b are with the other outer terminal 6b by means of a supply line 5b Next, a method of manufacturing the piezoelectric oscillator described above will be described.

First, be as starting materials, an Ag-containing Ag compound, a Li-containing Li compound, Nb-containing Nb compound, a Ta-containing Ta compound containing a metal element M1 M1 connection, one a metal element M2 containing M2 compound and a metal element M3-containing M3 compound generated.

Then These compounds are weighed to a predetermined composition to produce, which is represented by the general formula (A). The weighed compounds are put into a grinding media like Zirconium-containing ball mill given and in a solvent mixed like deionized water or ethanol for 4 to 24 hours, to create a slip. Further, in this step, a Dispersants such as sorbitan are preferably added to the Continue to mix compounds evenly.

Then, the slurry is dried and calcined under an oxidizing atmosphere at a temperature of 800 to 1,100 ° C for 1 to 24 hours to obtain a calcined material. This calcined material, a solvent such as deionized water or ethanol and a binder such as a polyvinyl alcohol resin are placed in a ball mill containing a grinding media and mixed and pulverized and then dried. Then, the resulting dried powder is formed into a prism shape by uniaxial pressing, for example, and then sintered under an oxidizing atmosphere at a temperature of 950 to 1200 ° C for 3 to 10 hours. Thereby, piezoelectric ceramics formed from the piezoelectric ceramic composition described above become 1a and 1b produced.

Then, a conductive paste containing a conductive material such as Ag is generated. The conductive paste on the front and back sides of the piezoelectric ceramics 1a and 1b is applied and is dried to form conductive layers. Then, a polarization in the thickness direction of the piezoelectric ceramics becomes 1a and 1b by applying a predetermined voltage at a predetermined temperature for a predetermined period of time.

Then the first piezoelectric ceramic 1a masked at sections that the outer electrode three and the inner electrode 2 correspond. The conductive layer on the exposed portion was removed with a solvent. Thus, the outer electrode becomes three at the front of the first piezoelectric ceramic 1a and the inner electrode 2 at the rear of the first piezoelectric ceramic 1a educated. Analogously, the second piezoelectric ceramic 1b masked at a portion of the outer electrode 4 and the conductive layer on the exposed portion was removed with a solvent, around the outer electrode 4 at the rear of the second piezoelectric ceramic 1b to build

Then an epoxy adhesive on the surface (at the outer electrode 4 not arranged) of the second piezoelectric ceramic 1b applied. The second piezoelectric ceramic 1b and the first piezoelectric ceramic 1a are stacked and glued together so that their polarization directions are in the same direction. Thereby, a piezoelectric oscillator is manufactured.

In the piezoelectric oscillator thus produced, the piezoelectric ceramics are 1a and 1b formed from the piezoelectric ceramic composition described above. Therefore, the piezoelectric oscillator has a suitably high relative dielectric constant εr and a good piezoelectric characteristic stably having a high electromechanical coupling factor k ₃₃ and the piezoelectric constant d ₃₃ .

in the Specifically, a piezoelectric element having a high relative Dielectric constant εr of 600 or more. Therefore, the impedance matching becomes favorable the provision of a piezoelectric oscillator of small size and with a desired one Allow impedance.

Further, a highly reliable piezoelectric oscillator having an electromechanical coupling factor k ₃₃ of 25% or more and a piezoelectric constant d ₃₃ of 50 pC / N or more and further having a piezoelectric characteristic having a Curie temperature Tc of 200 ° C. or more achieved, be provided.

When next a second embodiment of the invention will be described.

A piezoelectric ceramic composition according to the second embodiment of the present invention is represented by the general formula (B): (1-n) (Ag _1-x Li _x ) _m (Nb _1-y Ta _y ) O ₃ -nM4M5O ₃ (B).

In of the formula, M4 represents a divalent metal element and M5 represents a tetravalent metal element. For the same reasons as in the first version become the molar ratios x, y, m and n are adapted to satisfy the above-mentioned expressions (1) to (4).

In other words, in the second embodiment, a perovskite oxide in which a divalent metal element M4 in the A site of the second complex oxide is solid-solved and a tetravalent metal element M5 is dissolved in the B site is used as the second complex oxide. When the second complex oxide form shown M4M5O ₃ is formed as in the first embodiment in a by the composition formula, a piezoelectric ceramic composition having a suitably high relative dielectric constant .epsilon..sub.R and a good piezoelectric property stably a high electromechanical coupling factor k _33, a high piezoelectric constant d ₃₃ and the Curie temperature Tc shows, are provided.

Further, examples of the bivalent metal element M4 include Ba, Sr, Ca and Mg. Examples of the tetravalent metal element M5 include Ti, Zr, Sn and Hf. By using these metal elements as in the first embodiment, a piezoelectric ceramic composition having a high relative dielectric constant εr of 600 or more and having a piezoelectric property which achieves an electromechanical coupling factor k ₃₃ of 25% or more, a piezoelectric constant d ₃₃ of 50 pC / N or more, and a Curie temperature Tc of 200 ° C or more.

Further, by using the piezoelectric ceramic composition (general formula (B)) according to the second embodiment as in the first embodiment, a piezoelectric oscillator similar to that shown in FIG 1 and 2 is shown.

The present invention is not limited to the above-described embodiments. As an embodiment of the piezoelectric ceramic composition is a solid solution in which a second complex oxide (M1, M2) M3O ₃ or M4M5O ₃ in a first complex oxide (Ag, Li) (Nb, Ta) O is solid-solved _3, preferably as described above. The second complex oxide (M1, M2) M3O ₃ or M4M5O ₃ but, in the first complex oxide (Ag, Li) (Nb, Ta) O ₃ can not be completely solid-solved, and may be partly present in a grain boundary. Furthermore, the second complex oxide (M1, M2) M3O ₃ or M4M5O ₃ as a mixture with the first complex oxide (Ag, Li) (Nb, Ta) O are present. ₃

In the embodiments described above, the dielectric ceramics 1a and 1b formed by compression molding. However, the piezoelectric ceramic material body may be formed by film formation. In other words, a piezoelectric ceramic material body can be prepared by wet-milling ceramic raw materials to form a ceramic slurry, processing the resulting ceramic slurry into ceramic green sheets by a doctor blade method, coating a predetermined number of green ceramic sheets, and sintering the layered green sheets.

at the embodiments described above is a piezoelectric oscillator as an example of the piezoelectric Elements described, but the same can be analogous to piezoelectric Actuators, piezoelectric filters, piezoelectric buzzer and piezoelectric Sensors are applied.

When next Examples of the present invention will be described in detail.

example 1

First, powders of Ag ₂ O, Li ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , Bi ₂ O ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , TiO ₂ , ZrO ₂ , SnO ₂ and HfO _{2 were} weighed to obtain the compositions shown in Table 1. Each of the weighed compositions was calcined under an oxidizing atmosphere at a temperature of 850 to 1,100 ° C for 10 hours by means of an electric furnace to obtain a calcined material.

This calcined material was wet milled. Then, 100 parts by weight of this calcined material and 5 parts by weight of a polyvinyl alcohol resin serving as a binder were mixed. The resulting mixture was dried and then formed by uniaxial pressing at a pressure of 9.8 × 10 ⁸ Pa into a prismatic mold 12 mm high, 12 mm wide and 2.5 mm thick and then under an oxidizing atmosphere at a temperature of 950 to 1200 ° C sintered for 3 to 10 hours to obtain a piezoelectric ceramic.

Then was applied to both the front and the back of the piezoelectric Ceramic applied an Ag paste and then fired at 800 ° C. Then, by applying a DC voltage of 20 to 100 kV / cm at the piezoelectric ceramic in an insulating oil bath a temperature of 40 to 150 ° C over 10 to 30 min. performed a polarization treatment.

Then The piezoelectric ceramic with a cutter was prisms with 2 mm height, 2 mm wide and 3 mm thick cut. So were piezoelectric Elements of samples Nos. 1 to 38 are provided.

Then, each of the piezoelectric elements of Samples Nos. 1 to 38 was measured for relative permittivity εr, thickness-modulating electromechanical coupling factor k _33, thickness vibration piezoelectric constant d _33, and Curie temperature Tc.

The relative dielectric constant εr, the electromechanical coupling factor k ₃₃ and the piezoelectric constant d ₃₃ were determined by a resonance-antiresonance method using an RF impedance analyzer (HP4194A: Hewlett-Packard).

Further, the temperature dependency of the electromechanical coupling factor k _{33 was} found, and a temperature at which the electromechanical coupling factor k ₃₃ becomes zero by a temperature rise, namely, a temperature at which the piezoelectric property disappears was found to be Curie temperature Tc.

• *: Wert außerhalb des Bereichs der vorliegenden Erfindung

Table 1 shows the compositions of Sample Nos. 1 to 38 and the measurement results. [Table 1] Sample No. (1-n) (Ag _1-x Li _x ) _m (Nb _1-y Ta _y ) O ₃ -n (M1, M2) M ₃ O ₃ Relative dielectric constant εr Electromechanical coupling factor k ₃₃ (%) Piezoelektr. ₃₃ constant (pC / N) Curie temperature Tc (° C) x y m n M ₁ M ₂ M ₃ 1* 0100 00:00 1.0 00:00 - - - 304 41 55 290 2 0075 00:00 1.0 12:10 Bi N / A Ti 800 45 110 230 three 0100 00:00 1.0 12:05 Bi N / A Ti 1000 48 100 270 4 0150 00:00 1.0 12:01 Bi N / A Ti 750 35 70 300 5 0200 00:00 1.0 12:05 Bi N / A Ti 650 28 65 290 6 0300 00:00 1.0 12:10 Bi N / A Ti 1500 30 70 300 7 0100 12:05 1.0 12:05 Bi N / A Ti 650 44 85 260 8th 0100 12:10 1.0 12:01 Bi N / A Ti 700 45 50 250 9 * 0100 12:05 1.0 12:20 Bi N / A Ti 450 15 45 140 10 0075 12:05 1.0 12:05 Bi N / A Ti 650 40 60 220 11 0150 12:10 1.0 12:05 Bi N / A Ti 680 45 55 200 12 * 0400 12:10 1.0 12:05 81 N / A Ti Not polarized 13 * 0100 00:00 1.0 12:15 Bi N / A Ti 2000 18 30 100 14 0100 00:00 1.0 12:05 B1 Li Ti 950 45 95 280 15 0150 00:00 1.0 12:01 B1 K Ti 700 30 65 310 16 0100 00:00 1.0 12:05 Bi Ag Ti 950 43 90 280 17 0150 00:00 1.0 12:01 Bi N / A Zr 800 38 75 310 18 0075 12:05 1.0 12:05 Bi N / A Zr 680 43 65 230 19 0150 12:10 1.0 12:05 Bi N / A Zr 700 46 60 210 20 0100 00:00 0.98 12:05 Bi N / A Ti 1000 48 100 270 21 0150 00:00 0.98 12:01 Bi N / A Ti 750 35 70 300 22 0150 00:00 0.98 12:01 Bi K Ti 700 30 65 310 23 0100 00:00 0.98 12:05 B1 Ag Ti 950 43 90 280 24 0150 00:00 0.98 12:01 Bi N / A Zr 800 38 75 310 25 * 0100 12:05 0.97 12:05 Bi N / A Ti Not polarized 26 0100 00:00 0.98 12:05 Bi Na / Li (0.5 / 0.5) Ti 980 45 90 260 27 0150 00:00 0.98 12:01 Bi Na / K (0.5 / 0.5) Ti 780 35 65 300 28 0150 00:00 0.98 12:01 Bi Na / Ag (0.5 / 0.5) Ti 680 28 60 300 29 0100 00:00 0.98 12:05 Bi Li / Ag (0.5 / 0.5) Ti 900 40 85 270 30 0100 00:00 1.0 12:05 Bi Li Zr 900 42 90 270 31 0150 00:00 1.0 12:01 Bi K Zr 650 26 60 310 32 0100 00:00 1.0 12:05 Bi Ag Zr 900 40 85 280 33 0075 00:00 1.0 12:10 Bi N / A Hf 780 40 80 210 34 0100 00:00 1.0 12:05 Bi N / A Hf 950 42 85 230 35 0100 00:00 1.0 12:05 Bi N / A sn 900 35 70 240 36 0150 00:00 1.0 12:01 Bi N / A sn 650 27 55 270 37 * 0050 00:00 1.0 12:01 Bi N / A Ti 300 43 60 150 38 * 0100 12:20 1.0 12:01 Bi N / A Ti 250 45 55 160

• *: Value out of the range of the present invention

As is apparent from Table 1, it was confirmed that the relative dielectric constant was .epsilon..sub.R a low value of 304, since the composition of Sample Nos. 1 not the second complex oxide (M1, M2) M3O containing _3.

Further, it was confirmed that the Curie temperature Tc was a low value of 140 ° C and the relative dielectric constant εr, the electromechanical coupling factor k ₃₃ and the piezoelectric constant d _{33 were} also low because the composition of Sample No. 9 had a high molar ratio n of 0.20.

at the composition of Sample No. 12 had the molar ratio x a high value of 0.400 and therefore the sintering property was poor and the insulation resistance is low. This allowed the polarization treatment not executed become.

Since the molar ratio n in the composition of the sample No. 13 was 0.15, it was confirmed that the molar amount of the second complex oxide (M1, M2) M3O _{3 was} too large, so that the electromechanical coupling factor was lowered to 18%, and also the piezoelectric constant d ₃₃ and the Curie temperature Tc were lowered.

There the molar ratio m in the composition of Sample No. 25 is a low value of 0.97, the composition of the B site (Na, Ta) of the first was complex oxide too large. Therefore, the sintering property and the insulation resistance deteriorated was lowered. As a result, the polarization treatment could not accomplished become.

In the composition of the sample No. 37, since the molar ratio x was 0.050, which was too small, it was confirmed that the Curie temperature TC was a low value of 150 ° C and the relative permittivity εr, the electromechanical coupling factor k ₃₃ and the piezoelectric constant d _{33 were} also too low.

Since the molar ratio y was a high value of 0.2 in the composition of Sample Nos. 38, it was confirmed that the Curie temperature Tc was a low value of 160 ° C and .epsilon..sub.R the relative dielectric constant, the electromechanical coupling factor k ₃₃ and the piezoelectric constant d _{33 were} also low.

Since in each composition of Sample Nos. 2 to 8, 10, 11, 14 to 24 and 26 to 36, the molar ratios x, y, m and n were within the ranges of the present invention, ie 0.075 ≦ x <0.4, 0 ≦ y <0.2, 0.98 ≦ m ≦ 1.0 and 0.01 ≦ n ≦ 0.1, and the second complex oxide (M1, M2) M3O ₃ in the first complex oxide (Ag _1-x Li _x ) (Nb _1-y Ta _y ) O ₃ was dissolved, it was confirmed that the dielectric member had a high relative dielectric constant εr of 600 or more and was excellent in piezoelectric properties, so that the electromechanical coupling factor k _{33 was} 25% or was more, the piezoelectric constant d _{33 was} 50 pC / N or more and the Curie temperature Tc was 200 ° C or more.

Example 2

Powders of Ag ₂ O, Li ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , BaCO ₃ , SrCO ₃ , CaCO ₃ , MgO, TiO ₂ , ZrO ₂ , SnO ₂ and HfO _{2 were} weighed out to give the in Table 2 shown compositions. Each of the weighed compositions was calcined under an oxidizing atmosphere at a temperature of 800 to 1,100 ° C for 10 hours by means of an electric furnace to obtain a calcined material.

Then were piezoelectric elements of samples Nos. 41 to 80 means of the same process and process as prepared in Example 1.

Then, each of the piezoelectric elements of Sample Nos. 41 to 80 was measured for the relative permittivity εr, the electromechanical coupling factor k ₃₃ for thickness vibration, the piezoelectric constant d ₃₃ for thickness vibration and the Curie temperature Tc by the same method and process as in Example 1 measured.

• *: Wert außerhalb des Bereichs der vorliegenden Erfindung

Table 2 shows the compositions of Sample Nos. 41 to 80 and the measurement results. [Table 2] Sample No. (1-n) (Ag _1-x Li _x ) _m (Nb _1-y Ta _y ) O ₃ -nM4M5O ₃ Relative dielectric constant εr Electromechanical coupling factor k ₃₃ (%) Piezoelektr. Constant ₃₃ (pC / N) Curie temperature Tc (° C) x y m n M4 M5 41 * 0100 00:00 1.0 00:00 - - 304 41 55 290 42 0075 00:00 1.0 12:10 Ba Ti 800 47 130 210 43 0100 00:00 1.0 12:05 Ba Ti 950 49 110 250 44 0150 00:00 1.0 12:01 Ba Ti 700 37 80 300 45 0200 00:00 1.0 12:05 Ba Ti 630 31 75 280 46 0300 00:00 1.0 12:10 Ba Ti 1500 34 90 290 47 0100 12:05 1.0 12:05 Ba Ti 640 47 100 250 48 0100 12:10 1.0 12:01 Ba Ti 670 47 55 250 49 * 0100 12:20 1.0 12:01 Ba Ti 400 21 50 130 50 * 0100 12:45 1.0 12:01 Ba Ti 550 Not measurable 51 * 0000 12:15 1.0 0.1 Ba Ti 400 Not measurable 52 0075 12:05 1.0 12:05 Ba Ti 620 43 70 210 53 0150 12:10 1.0 12:05 Ba Ti 660 48 65 200 54 * 0400 12:10 1.0 12:05 Ba Ti Not polarized 55 * 0100 00:00 1.0 12:15 Ba Ti 1800 20 40 100 56 0100 00:00 1.0 12:05 Ba / Sr (0.5 / 0.5) Ti 880 46 105 260 57 0150 00:00 1.0 12:01 Ca Ti 640 32 70 290 58 0100 00:00 1.0 12:05 mg Ti 860 44 95 260 59 0150 00:00 1.0 12:01 Ba Zr 770 40 80 300 60 0075 12:05 1.0 12:05 Ba Zr 650 46 80 220 61 0150 12:10 1.0 12:05 Ba Zr 670 48 75 210 62 0100 00:00 0.98 12:05 Ba Ti 910 50 115 250 63 0150 00:00 0.98 12:01 Ba Ti 720 37 80 280 64 0150 00:00 0.98 12:01 Sr Ti 630 32 70 290 65 0100 00:00 0.98 12:05 Ba / Ca (0.5 / 0.5) Ti 890 45 100 270 66 0150 00:00 0.98 12:01 Ba Zr 740 40 85 290 67 * 0100 12:05 0.97 12:05 Ba Ti Not polarized 68 0100 00:00 0.98 12:05 Ba / Mg (0.5 / 0.5) Ti 910 46 95 240 69 0150 00:00 0.98 12:01 Ca / Sr (0.5 / 0.5) Ti 700 36 70 290 70 0150 00:00 0.98 12:01 Ca / Mg (0.5 / 0.5) Ti 600 29 65 290 71 0100 00:00 0.98 12:05 Sr / Mg (0.5 / 0.5) Ti 820 41 90 250 72 0100 00:00 1.0 12:05 Ba Zr 840 44 100 250 73 0150 00:00 1.0 12:01 Ba Zr 620 29 65 300 74 0100 00:00 1.0 12:05 Ba / Ca / Sr / Mg (0.25 / 0.25 / 0.25 / 0.25) Zr 870 42 95 260 75 0075 00:00 1.0 12:10 Ba Hf 780 43 95 200 76 0100 00:00 1.0 12:05 Ba Hf 900 44 95 210 77 0100 00:00 1.0 12:05 Ba sn 870 38 80 220 78 0150 00:00 1.0 12:01 Ba sn 620 30 60 250 79 * 0050 00:00 1.0 12:01 Ba Ti 280 45 70 140 80 * 0100 00:00 1.1 12:05 Ba Ti Not polarized

• *: Value out of the range of the present invention

Since the composition of Sample Nos. 41 did not contain the second complex oxide M4M5O _3, the relative dielectric constant was .epsilon..sub.R a low value of 304, as in the composition of the sample no. 1 in Example 1.

Since, in the composition of the sample No. 49, the molar ratio y was a high value of 0.20, it was confirmed that the Curie temperature Tc was a low value of 130 ° C and the relative permittivity εr, the electromechanical coupling factor k ₃₃ and the piezoelectric constant d _{33 were} also low.

In the composition of Sample No. 50, the molar ratio y was a high value of 0.45. Therefore, resonance antiresonance was not recognized in the polarization treatment, and electromechanical coupling factor k ₃₃ , piezoelectric constant d _33, and Curie temperature Tc could not all be measured.

In the composition of Sample No. 51, the molar ratio x was zero. Therefore, as in the composition of Sample No. 50, in the polarization treatment, resonance antiresonance was not recognized, and electromechanical coupling factor k ₃₃ , piezoelectric constant d ₃₃ and Curie temperature Tc could not be measured all.

at the composition of Sample No. 54 was the mole ratio x a high value of 0.400 and therefore the sintering property was poor and the insulation resistance is low. This allowed the polarization treatment not executed become.

Since, in the composition of the sample No. 55, the molar ratio n was 0.15 and therefore the molar amount of the second complex oxide M4M5O _{3 was} excessive, it was confirmed that the electromechanical coupling factor k _{33 was} lowered to 20% and the piezoelectric constant d ₃₃ and the Curie temperature Tc were also lowered.

There in the composition of Sample No. 67, the molar ratio m was a low value of 0.97, the composition of the B site was (Na, Ta) of the first complex oxide excessively. Therefore, the sintering property became deteriorates and the insulation resistance lowered. This could the polarization treatment will not be performed.

Since in the composition of the sample No. 79, the molar ratio x was 0.050, which is too small, it was confirmed that the Curie temperature Tc was a low value of 140 ° C and the relative dielectric constant εr, the electromechanical coupling factor k ₃₃ and the piezoelectric constant d _{33 were} also low.

There in the composition of Sample No. 80, the molar ratio m a high value of 1.1, the composition was the first complex Oxides of A site overly. Therefore the sintering property was deteriorated and the insulation resistance lowered. As a result, the polarization treatment could not be performed.

Since in each of the compositions of sample Nos. 42 to 48, 52, 53, 56 to 66 and 68 to 78, the molar ratios x, y, m and n were within the ranges of the present invention, ie 0.075 ≦ x <0.4, 0 ≦ y <0.2, 0.98 ≦ m ≦ 1.0 and 0.01 ≦ n ≦ 0.1, and the second complex oxide M4M5O ₃ in the first complex oxide (Ag _1-x Li _x ) _m ( Nb _1-y Ta _y ) O ₃ , it was confirmed that the dielectric element had a high relative dielectric constant εr of 600 or more and had excellent piezoelectric properties, so that the electromechanical coupling factor k _{33 was} 25% or more piezoelectric constant d _{33 was} 50 pC / N or more and the Curie temperature Tc was 200 ° C or more. Further, (56 Sample Nos. 65, 68 to 71 and 74), it was confirmed that the desired piezoelectric properties described above can be provided, even if more than one metal element in the A-site composition of the second complex oxide M4M5O ₃ was solid-solved ,

Claims (6)

A piezoelectric ceramic composition having a main component represented by the general formula {(1-n) (Ag _1-x Li _x ) _m (Nb _1-y Ta _y ) O ₃ -n (M1, M2) M ₃ O ₃ }) M1 represents a trivalent metal element, M2 represents a monovalent metal element and M3 represents a tetravalent metal element), where x, y, m and n are set as: 0.075 ≤ x <0.40; 0 ≤ y <0.2; 0.98 ≤ m ≤ 1.0 and 0.01 ≤ n ≤ 0.1. Piezoelectric ceramic composition according to claim 1, characterized in that M1 is Bi, M2 at least one element chosen from the group consisting of K, Na, Li and Ag and M3 is at least one Element selected from the group consisting of Ti, Zr, Sn and Hf. A piezoelectric ceramic composition having a main component represented by the general formula {(1-n) (Ag _1-x Li _x ) _m (Nb _1-y Ta _y ) O ₃ -nM4M5O ₃ } (wherein M 4 represents a divalent metal element and M5 represents a tetravalent metal element), where x, y, m and n are set as: 0.075 ≤ x <0.40; 0 ≤ y <0.2; 0.98 ≤ m ≤ 1.0 and 0.01 ≤ n ≤ 0.1. Piezoelectric ceramic composition according to claim 3, characterized in that M4 is selected from at least one element the group consisting of Ba, Sr, Ca and Mg is at least M5 an element selected from the group consisting of Ti, Zr, Sn and Hf. Use of a piezoelectric ceramic composition for a piezoelectric element, one of a piezoelectric element Ceramic composition according to any one of claims 1 to 4 formed ceramic sintered body as well as on the surface of the ceramic sintered body arranged outer electrodes includes. Use of a piezoelectric ceramic composition for a Piezoelectric element according to claim 5, characterized in that in the ceramic sintered body an inner electrode is embedded.